Policy makers and others are concerned that many young men today are only loosely attached to their children and their children's mothers. This concern has been fueled by rising rates of non-marital childbearing, delays in the age of marriage, increases in the share of children being raised in female-headed families, and the failure of some biological fathers to D'ovide economic support to their children. The aim of this proposal is to form a multi-disciplinary team of research collaborators who will meet on a regular basis to plan and conduct coordinated analyses on topics relating to the transition to fatherhood using multiple data sets. The four projects included in this proposal address the following related issues: 1. What are the economic, policy, psychological, and sociological factors that influence the timing of biological fatherhood and the circumstances under which fatherhood occurs? What is the role of men in the timing and circumstances of sexual initiation, contraceptive use, pregnancy, and childbearing? 2. What is the relationship between the transition to biological fatherhood and other transitions to adulthood, such as marriage, educational completion, and entry into the workforce? 3. What are the determinants of responsible fathering, and, in particular, what is the role of family process within and across generations? 4. What are the social, economic, policy, relationship and individual factors associated with men having additional births after they have already become fathers, and what factors lead men to have additional births, with more than one partner? Each project will conduct parallel analyses across multiple data sets, and similar data sets will be used across many of the projects. The data sets used in the four projects include National Longitudinal Survey of Youth 1997 and 1979;Add Health;National Survey of Adolescent Males;National Survey of Family Growth; Fragile Families;Early Head Start;Early Childhood Longitudinal Study, Birth Cohort;National Survey of Families and Households;Panel Study of Income Dynamics-CDS. Our strategy will enable us to obtain a much fuller understanding of the factors that influence the transition to fatherhood. We also propose two infrastructure cores: (A) Administration and Dissemination and (B) Data Management and Methodology.